Electric motor brush holder,cap and spring



M r h 1969 A. J. PETERSEN ETAL ELECTRIC MOTOR BRUSH HOLDER, CAP ANDSPRING Filed y 25, 1967 hllm ALLEN J PETERSEN EVERETT K. HANSEN A7'TORNEV a United States Patent 7 Claims ABSTRACT OF THE DISCLOSURE Anelectric motor brush holder with the motor housing having notches in theend for slidably receiving the brush holders. A cap fits on the brushholder to enclose the brush and its back-up spring. The spring has anenlarged portion in contact with a sleeve which slidably receives thebrush, and the enlarged portion provides electrical contact between thebrush and the sleeve.

Background of the invention This invention relates to an electric motorand its brush holder, and, more particularly, it relates to a means forsecuring the brush in position with respect to the com mutator withoutthe requirement for any screw threads or other attaching means requiringa tool.

Brush holders are commonly attached to the motor housing by means ofthreads or other structure which retains the holder on the housing.Also, the brush itself is commonly retained in the holder by means of athreaded cap disposed behind the back-up spring of the brush.

The prior art also has brush holders and brushes which are securedwithout threaded means or the like. However, maintaining these prior artholders in the desired aligned position with respect to the commutatorrequires expensive and complicated mountings for the brush holder.Likewise, securing the brush back-up spring in the holder, even wherethreaded caps or the like are not employed. also requires expensive andcomplicated covers and like means. These prior art structures commonlyrequire tools for assembly and disassembly of the brush holder both withrespect to the motor housing as well as with regard to the removal ofthe brush from the holder. Examples of these prior art units are shownin patents of the United States under Nos. 2,045,293, 2,537,714, and2,683,826.

Still further, the prior art brush holders do not provide a reliablemeans for conducting the electric current from the brush to the electricwire which makes connection with the brush. In this regard, the presentinvention provides an eflicient means for conducting electric currentfrom the brush and through the brush sleeve and to the wire commonlyconnected to the brush sleeve. With the present invention, the commonlyprovided wire extending from the outer end of the brush and to the brushsleeve by means of a connecting disk or cap is not necessary. That is,the electric connection can be made through the back-up spring extendingbetween the brush and being in electric contact with the brush sleeve.

It is also the object of this invention to provide a brush holder whichis eflicient in conducting electric current, is accurately aligned withthe commutator, which is sturdy and free of undo exposure to breakage,and is not susceptible to damage. Additionally, the holder has theaforementioned features, and it is easy and inexpensive to manufacture,repair, and it is compact with the motor main parts of the "housing andthe armature.

Still another object and point of improvement in the present inventionis the provision of a brush holder which provides for inspection,repair, replacement, and the like of the brush without requiring the useof tools in that 3,431,446 Patented Mar. 4, 1969 only a snap-cap isemployed. Further, the cap provides for assurance of electrical contactbetween the brush the brush sleeve in that the cap engages the back-upspring for maintaining contact between the spring and the brush sleeve.

Brief description of the drawing FIG. 1 is a side elevational view ofone embodiment of this invention, with parts thereof broken away.

FIG. 2 is an enlarged end view of a portion of FIG. 1 shown sectioned,and taken along the line 22 of FIG. 1.

FIG. 3 is a bottom plan view of FIG. 2.

FIG. 4 is a side elevational view of the brush holder of FIG. 2.

FIGS. 5 and 6 are bottom and side views, respectively, of the cap shownin FIG. 2.

FIGS. 7 and 8 are end elevational and side elevational views,respectively, of the back-up spring shown in FIG. 2.

FIGS. 9, 10 and 11 are sectional views similar to FIG. 2 but showingdiiferent embodiments of the brush holder assembly.

Detailed description of the shown embodiments A motor housing 10 isshown to contain the usual stator 11, and armature 12 with commutator13. Armature shafts 14 and 16 extend beyond the generally cylindricallyshaped housing 10, and beyond the end caps 17 and 18 which are shown tobe bolted to the housing main body 10. Thus the armature 12 and itscommutator 13 are mounted in the housing for the desired rotation, andbrush holder assemblies 19 are mounted on the housing body 10 for theusual purpose of disposing the brushes 21 in sliding contact with thecommutator 13. The housing 10 has notches 22 which slidably receive thebrush assemblies 19, and, more particularly, the notches 22 snuglyslidably receive the brush holders 23 which are made of a non-conductivematerial, such as plastic. The housing end cap 17, when fastened to thehousing body 10 by the screws 24, or other conventional means, securethe brush holders 23 to the body 10 in the position shown in FIGS. 1, 2and 3. Thus the assemblies 19 can be readily slid onto and off of thebody 10 for the desired positioning and alignment of the brushes 21 withthe commutator 13.

The brush holders 23 have openings 26 extending therethrough, and abrush sleeve 27 is disposed in the opening 26 in an axially fixedposition. Thus the brush holder 23 has an end 28 extending externally ofthe housing 10 and terminating in an outer edge or surface designated29. The opposite sides of the holder 23 have grooves 31 which slidablyfit the thickness of the housing body 10 along the notch 22. Thus theholder 23 is held in a fixed position with respect to the body 10,except for sliding the holder 23 011 the body 10 when it is desired toremove the holder 23, and of course also when the assembly is made, theholder 23 can be slid onto the body 10.

FIG. 1 shows that electric wires 32 are in contact with the inner endsof the brush sleeves 27, and these wires 32 therefore make electriccontact with the brush sleeves 27, in the usual manner. Also, in theusual manner, the brushes 21 are slidable in the brush sleeves 27 andmake electric contact with the sleeves 27.

A cap or a closure 33 extends over the brush holder surface 29 and flushtherewith, and the cap is also preferably made of a plastic materialwhich is not electrically conductive. The cap 33 is also made of aflexible material so that it can be placed onto the holder 23, in theposition shown, and it can be removed from the holder 23, both withoutrequiring any special tools but necessitating only finger pressure. Thusthe cap 33 has projections or tangs 34 which extend inwardly on the cay33 on opposite sides thereof, and the tangs 34 snap into the notches oropenings 36 on opposite sides of the brush holder 23. Thus the mainportion 37 of the cap 33 extends over the brush holder surface 29 toclose the upper end of the opening 26.

FIGS. 2, 7 and 8 show a brush spring 38 which is in electric contactwith the brush at the spring end 39 and which is in electric contactwith the upper surface 41 of the brush sleeve 27. That is, the spring 38has an enlarged portion or coil 42 which is generally of the size of thecross section of the brush sleeve 27 so that the coil 42 rests upon thesurface 41, as shown in FIG. 2. Also, the spring 38 has the upper end 43in contact with the cap 33 to urge the spring coil 42 downwardly intoelectric contact with the brush sleeve surface 41. Therefore, electriccontact is assured between the brush 21 and the brush sleeve 27.

Finally, it should be noted that the cap 33 has a centrally disposedprojection 44 which extends downwardly toward the spring 38 andtherefore it guides the spring 38 both by keeping the spring fromslipping out of a central position and by urging the spring into contactwith the sleeve 27, as indicated in FIG. 3.

FIG. 9 shows a different configuration of the spring, and here a spring46 has an enlarged coil 47, like the coil 42, in contact with the upperend of the brush sleeve 27 The spring 46 also has a disk 48 attached tocoils 49 on the spring 46, and the disk 48 is urged downwardly by theprojection 44 and, with the spring coils 49, the enlarged coil 47 isurged against the brush sleeve 27. In this instance, a flexible wire 51extends between the brush 21 and the disk 48 to make electric contacttherebetween for conducting current therebetween. However, current isconducted along the spring 46 and to the sleeve 27 by means of theenlarged coil 47, as in the embodiment shown in FIG. 2, in addition tothe function of the flexible wire 51.

FIG. shows a spring 52 extending to a disk 53, and another spring 54 isshown above the disk 53 and is in contact with the cap 33. Thus thespring 54 is urged downwardly onto the disk 53 which in turn is urgedinto contact with the upper surface of the sleeve 27 to make electriccontact therewith.

FIG. 11 shows a spring 56 disposed between the brush 21 and cap 33. Thespring has an enlarged coil 57 at its upper end, and the coil 57 is of asize to be in contact with the upper surface 41 of the sleeve 27 whenthe coil 57 is pressed downwardly by the cap 33. That is, the spacebetween the brush sleeve surface 41 and the cap 33 is such that the coil57 snugly occupies the space so that it is in contact with the surface41, as desired. Here it will also be noted that the cap projection 44,being disposed centrally on the cap 33, assures that the spring coil 57will be held in contact with the sleeve 27. This feature is also shownin FIG. 3 where it will be observed that the sleeve 27 is slightly offcenter on the brush holder 23 so that the centrally located projection44- will maintain the spring aligned with the sleeve 27 and also incontact with the upper surface 41. It will be noted that in theseseveral embodiments the length of the sleeve 27, or at 60 least itsspacing of its upper surface 41 from the cap portion 37 may vary.

What is claimed is:

1. In an electric motor, a housing, a stator and an armature disposed insaid housing and including a commutator, a cover removably connected toan end of said housing for rotatably supporting said armature andenclosing said stator and said armature in said housing, a brush holderon said housing and extending externally of said housing in an endhaving a terminal edge, a brush sleeve disposed in said holder and beingcountersunk therein to terminate short of said terminal edge of saidbrush holder extending from said housing, a brush removably disposed insaid brush holder and being in abutment with said commutator, a closureremovably attached to the externally extending portion of said brushholder for securing said brush in said brush holder, a coil springdisposed between said closure and said brush for yieldingly urging saidbrush into abutment with said commutator, the improvement comprisingsaid closure being a flexible cap to be snapped onto and off from saidedge of said brush holder and, extending over said spring and urgingsaid spring into the direction of said brush, and said spring having anenlarged piece thereon disposed over the end of said brush sleeve and incontact therewith and arranged to be urged into contact with said sleeveby said cap.

2. The subject matter of claim 1, wherein said cap is a plastic capincluding tabs for removably attaching to said brush holder by fingerpressure only, and said brush holder being grooved and said housingbeing notched for removably receiving said brush holder adjacent saidcover, all being arranged to eliminate screw threads for holding saidbrush holder and said cap.

3. The subject matter of claim 1, wherein said enlarged piece on saidspring is an enlarged coil of said spring and making electrical contactwith said brush sleeve.

4. The subject matter of claim 3, wherein said enlarged coil isintermediate along the length of said spring, and one end of said springis connected to said brush and the other end of said spring is inabutment with said cap.

5. The subject matter of claim 3, wherein said enlarged coil is on oneend of said spring, and said brush sleeve is spaced from said cap adistance equal to the thickness of said enlarged coil for urging thelatter against the end of said brush sleeve.

6. The subject matter of claim 1, including a length of spring extendingbetween said cap and said enlarged piece for urging the latter intocontact with said brush sleeve.

7. The subject matter of claim 1, wherein said cap includes a projectionfor guiding said spring axially of said brush holder.

References Cited UNITED STATES PATENTS 1,933,628 11/1933 Kitto 3l0--2473,152,274 10/1964 Fox 31{)247 3,187,214 6/1965 Brezosky 310-239 FOREIGNPATENTS 795,998 6/1958 Great Britain. 960,557 3/1957 Germany.

WARREN E. RAY, Primary Examiner.

R. SKUDY, Assistant Examiner,

